Planning for the future.. is a 700W ModXStream PSU enough to push 4890s in CrossFire?

[BrokenVisage]

Here it is..

For my new build I decided to bite the rebate bullet and go for this OCZ PSU @ $60. Had lots of great reviews and 700W seemed like enough power to push everything I'm getting.

The computer is going to be built around a Phenom X3 720 and a 4890XT for now, but in the future I would like to go CrossFire. I just want to get some opinions on whether this will be enough to power a second 4890XT cleanly. I do plan to OC quite a bit, especially the Phenom which should OC quite easily. The PSU hasn't even shipped yet so I can always cancel/refuse if the general feeling is it won't be enough.

There are 100+ reviews for this thing but I honestly haven't seen 1 that tested it on an SLi/CrossFire setup. Also, I would probably have to get an adapter to turn one of the 4 pin molex cables into one that can fit into a second 4890. So the more I thought about it the more it seemed like this wasn't meant for "beastly" cards, but maybe you guys could put my mind at ease. Thanks.

 

[yh125d]

You'd need to get two pci-e connectors from the molex connectors, but other than that it's enough power yeah. Although I would have gone for the corsair 650TX

 

[BrokenVisage]

Originally posted by: yh125d
You'd need to get two pci-e connectors from the molex connectors, but other than that it's enough power yeah. Although I would have gone for the corsair 650TX

Well I just looked and the card does come with 2 adapters to turn 4 molexs into 2 6-pin PCI-e plugs. It seems that people frown upon using these but is there really any big performance/saftey difference in using them? I would have gone for a PSU that came with 4 proper PCI-e plugs but they were all $40+ more for comparable power to this.

 

[jonnyGURU]

Cancel the order on the OCZ PSU.

It's a mediocre power supply (it does NOT have great reviews from anyone competent. See here: http://hardocp.com/article.htm...U2NiwsLGhlbnRodXNpYXN0 for a proper review) and now you're going to much things up more by having to use adapters.

Why skimp on a PSU? It's potentially a component you can keep through several upgrades, where as when you buy a POS, it can die and take out other components with it. It just doesn't make sense to me.

 

[DrMrLordX]

Ugh, that unit did not review well at 100% load (700W).

Also, OP, you said the unit comes with an adapter to turn 4 molex plugs into 2 6-pin pci-e connectors? If you're going to be running 4890s in Crossfire, won't you need 2 8-pin and 2 6-pin connectors? The base unit comes with 1 6-pin and 1 8-pin, so if you use the adapter, you'll wind up with 1 8-pin and 3 6-pin, which I suppose would require you to use a 6-pin to 8-pin adapter in addition to the molex-to-pci-e adapter. That would be kinda messy.

 

[yh125d]

In addition to Jonny and Dr, I'm surprised OCZ sells this as a 700w PSU. Technically it is, 552w on 12v, 150w on 3.3/5v, but most quality manufacturers, I've noticed, sell their PSU's with the overall rating only slightly higher than the 12v wattage alone. For example, the corsair 650TX has 624w on the 12v rails, almost 75w more than the 700w OCZ. 620HX has 600w on 12v. 850TX has 840w on 12v. PCP&C 750 has 720w on 12v. Antec TP-550 has 540w on 12v. Seasonic M12 SS-600HM 600W has 572w on 12v, and there are many more.


I would definitely thin about returning it for something more reputable.


Also, generally speaking there isn't a problem using adapters to get the needed pci-e cables, but there is a chance that if done improperly (in multi-rail PSUs) you can load too much on a single rail. If you end up doing that be sure to consult youe manual to see how the rails are split

 

[brblx]

as long as you don't try and pull all the video card power from one strand of PSU wiring, i don't see an issue with adapters.

however when jonnyguru tells you a psu is poo, i'd be inclined to believe him.

 

[Lunyone]

Here is what I'd consider for a X-fire setup:
$103 - $10 MIR = $93!! Corsair 750tx (has 4 x 6 + 2pin (8pin) PCI-e connectors and has 60A on the 12v rail = 720w!!)

$110 shipped!! PCP&C 750w which has 60A also on the 12v rail and comes with 2 x 6pin and 2 x 6+2 pin PCI-e power connectors)

$110 Antec 750w PSU w/2 x 6pin and 2 x 6+2pin PCI-e power connectors

Those are a few that I'd consider getting. There are others, but these would be a good place to start. Personally I'd just stick with a single GPU solution and just upgrade to the latest and greatest GPU when you feel you need to upgrade the GPU. This way you can save on electricity/cooling/other parts. With the savings on the extra parts for a SLI/X-fire setup you could use the savings for future upgrades.

If you go with a single GPU solution you can lower your power requirements on the PSU and only have to get a quality PSU in the 450-550w range, depending on all other parts that you select.

 

[BrokenVisage]

Originally posted by: DrMrLordX
Ugh, that unit did not review well at 100% load (700W).

Also, OP, you said the unit comes with an adapter to turn 4 molex plugs into 2 6-pin pci-e connectors? If you're going to be running 4890s in Crossfire, won't you need 2 8-pin and 2 6-pin connectors? The base unit comes with 1 6-pin and 1 8-pin, so if you use the adapter, you'll wind up with 1 8-pin and 3 6-pin, which I suppose would require you to use a 6-pin to 8-pin adapter in addition to the molex-to-pci-e adapter. That would be kinda messy.

It's funny.. I was looking at this installation packet that came with my card and it explicitly shows/tells you NOT to use two molex->pci-e adapters as connections.. even though they include 2 of them in the box! Also the OCZ PSU comes with a 6-pin and a 6+2-pin, so I knew I was safe with just running 1 card on it for now.

But yeah, I went ahead and got a 850W Corsair after figuring it would be the best way of doing things. Will end up actually being around the same price as the OCZ after 2 $30 rebates. Should have nooo concerns or questions about this one, it's a monster with impecable reviews that will be enough power for my needs and then some!

Unfortunately my other PSU order shipped out too though, so I'll have to refuse it and do a song and dance to have the merchant waive their restocking fee, but I'm happy I came to this conclusion before receiving it. Now all I need is some DDR3 memory and a case.

 

[BrokenVisage]

Originally posted by: jonnyGURU
Cancel the order on the OCZ PSU.

It's a mediocre power supply (it does NOT have great reviews from anyone competent. See here: http://hardocp.com/article.htm...U2NiwsLGhlbnRodXNpYXN0 for a proper review) and now you're going to much things up more by having to use adapters.

Why skimp on a PSU? It's potentially a component you can keep through several upgrades, where as when you buy a POS, it can die and take out other components with it. It just doesn't make sense to me.

Jonny it had great reviews from many different websites (some of which I would consider competent). But yes I saw the HardOCP review, I also saw them do a semi-retraction about it once clearing up some numbers that OCZ probably tried to get away with fudging. They did use some circular logic that made little sense to me and it smelled like a "paid" re-review to soften the blow of the first one, so I put little stock in both at that point. Does not take away from the fact they failed it, but as I understand they show no mercy with these tests and don't PSUs more often than not fail them anyway?

Na, plenty of websites and people gave this a good review on power, noise, build quality, etc.. which was enough to sway me at the time dispite the HardOCP review. Shame on me for not seeing I would need 4 proper PCI-e connectors to run CrossFire though, that's my bad judgement for not realizing this didn't have 4 so now I have to deal with sending this back. I'm sure you won't have a problem with my new choice though.

 

[HOOfan 1]

Originally posted by: BrokenVisage

Jonny it had great reviews from many different websites (some of which I would consider competent).
Na, plenty of websites and people gave this a good review on power, noise, build quality, etc.. which was enough to sway me at the time dispite the HardOCP review.

I can probably count on the fingers of 1 hand the sites that do proper reviews. What sites did you go by?

 

[WaitingForNehalem]

My next PSU will be either the Corsair HX750W or HX850W.

 

[yh125d]

Originally posted by: WaitingForNehalem
My next PSU will be either the Corsair HX750W or HX850W.

Me too. I would go for the 620w because it has plenty of power, but its an older model and I prefer single rail for simplicity. Now just gotta wait for a price cut or some rebates to kick in

 

[jonnyGURU]

Originally posted by: HOOfan 1

Originally posted by: BrokenVisage

Jonny it had great reviews from many different websites (some of which I would consider competent).
Na, plenty of websites and people gave this a good review on power, noise, build quality, etc.. which was enough to sway me at the time dispite the HardOCP review.

I can probably count on the fingers of 1 hand the sites that do proper reviews. What sites did you go by?

I'm curious too. Simply throwing a PSU in a PC and checking voltages with a multimeter, although commendable, is not a proper review. You can't load the PSU up to it's max capability, you can't run the PSU at it's max operating temperature and you can't measure ripple and noise without an oscope.

 

[HOOfan 1]

Originally posted by: yh125d

Originally posted by: WaitingForNehalem
My next PSU will be either the Corsair HX750W or HX850W.

Me too. I would go for the 620w because it has plenty of power, but its an older model and I prefer single rail for simplicity. Now just gotta wait for a price cut or some rebates to kick in

HX620 is an older model yes, but it is also a single rail unit, despite what the label says.

 

[yh125d]

Originally posted by: HOOfan 1

Originally posted by: yh125d

Originally posted by: WaitingForNehalem
My next PSU will be either the Corsair HX750W or HX850W.

Me too. I would go for the 620w because it has plenty of power, but its an older model and I prefer single rail for simplicity. Now just gotta wait for a price cut or some rebates to kick in

HX620 is an older model yes, but it is also a single rail unit, despite what the label says.

Well I have some other reasons for getting a "new" HX over the older ones. Noticably higher efficiency, more native pci-e cables, and a little more headroom since I plan on stepping up significantly power-wise soon